LEON

History

Tropical Cyclone Leon–Hanitra began as a weak tropical low that formed within the monsoon trough between the Cocos (Keeling) Islands and Christmas Island on 13 February 1989. Steered by a subtropical ridge lying to its south, the low drifted slowly on a west to west-southwest heading across the eastern Indian Ocean, gradually becoming better organised as it went.

On 17 February the system passed just to the south of the Cocos Islands, where it remained a developing low and produced only mean winds of around 45 km/h along with localised showers. No damage was reported there. Late the following day, 18 February, the low reached gale force and was named Leon by the Bureau of Meteorology's Tropical Cyclone Warning Centre in Perth. Continuing westward, Leon strengthened steadily as it neared the western boundary of the Australian region, reaching winds of about 85 km/h and a central pressure near 988 hPa before crossing 90°E on 19 February.

Warning responsibility then transferred to the Mauritius Meteorological Service, which renamed the system Hanitra. Over warm water and beneath low vertical wind shear, the cyclone intensified rapidly in the South-West Indian Ocean, peaking on 23 February as an intense tropical cyclone with 10-minute sustained winds of 150 km/h, gusts to around 230 km/h, and a minimum central pressure of roughly 940 hPa — equivalent to a Category 4 system. After peaking over the central Indian Ocean, Hanitra recurved towards the south-southeast ahead of an approaching mid-latitude trough. Rising wind shear and cooler seas eroded the system, which completed extratropical transition on 25 February before losing its identity at high latitudes by 1 March.

Leon–Hanitra never threatened the Australian mainland and made no landfall at any point in its roughly two-week life. Its only practical effect was on shipping, with high-seas gale and storm warnings issued for commercial lanes across the central Indian Ocean. No deaths, injuries or structural damage were attributed to the cyclone. It was one of a number of systems during a slightly above-average 1988–89 Australian region season.

Sources: Bureau of Meteorology report Wikipedia